Recover Special Attack:
Use controller 1 to pause and on controller 2 hold select and press:
S(7), T, C, X and let go of select.

Debug Mode:
Finish the game and save. Next highlight 'Continue' and hold:
Select+C for 10 secs.
The screen will go black.
Then let go of C but keep select held, and press:
C, X, S, T, C, X, S, T

Blue VF-1X-Plus Valkyrie:
Exceed 500 kills by the last mission. Then select the VF-1X Valkyrie. It can only be used in the last mission.

Recover Missiles:
Use controller 1 to pause the game then on controller 2 hold select and press:
C(7), T, S, X and then let go of select